On the Writer Guide 7.6, Chapter 4, Formatting Text, page 9 there is an error.
Under the subtitle (Title 2), “Paragraph background color”, there is a note saying (bold added):
If the paragraph has been indented from the right or left margin, the background color is not applied to the area of the indent. To extend the color to the margin, use a frame, table, or other method; see Chapter 6, Formatting Pages: Advanced.
CORRECTION:
This applies to character backgrounds, not paragraph backgrounds.
You can check here: Chapter 4, Formatting Text